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[SHOwn]

Well, the Redmobile III ran great today, doing errands, but I noticed on the way home when I opened my window at an ATM, she was making some strange clicking or tapping noises. Turns out, when I looked at it a little closer, the crank pulley for the AC was wobbling just a little, and the belts were cherping a little. Once I polled the splash shields off, I found two sheered off pulley bolts, and a third broke when I went to loosen it. Is this the dreaded short crank pulley issue? Is this the end of a great engine?  Man, this is a nice car, I hope not.

BTW, that's a 21mm main harmonic bolt.

[mitch1204]

Extracting the bolts is not a big issue. Finding out why it happened is your main concern. Did the last person not tighten the bolts properly?
You can read other threads. There was an issue with the earlier model Capris having a smaller crankshaft nose that cracked and sheared off. But that seems to me that would be the center bolt and possibly the whole balancer falling off. Worst case scenario is an engine swap. That looks like mechanic error and a chain of events with the bolts vibrating out.

Removing them bolts you need a good drill bit and extractor. They sell kits at the big name hardware stores by the drill bits. Use a center punch to start your hole and drill squared off straight into the bolt. If I remember correctly them bolts are only about a half inch long. They shouldn't be real hard to remove. Use some penetrating oil and soak them good.
If the extractor doesn't work don't panic yet. Step two is to drill out your hole a hair smaller than the base of the threads. The thread material will be remaining and will collapse easy for removal. You then chase your threads with a tap to clean them up for the new bolts. On the new bolts use thread lock and torque them down properly by the manual.
Hopefully the old bolts were just loose to begin with. The way the pulley shifted in the picture that's what looks like what happened. Either way you should pull the balancer to do the job. You can inspect the crankshaft at that time.
Since you are going that far you might want to consider changing the timing belt and water pump as you are halfway there. The hardest part of that job is pulling the harmonic balancer. Just a thought. The timing belt should be changed around 100,000 miles if it hasn't already. Maybe that's why the bolts were loose to begin with. Someone changed the timing belt and didn't tighten them bolts properly.
If you want a quickie fix you can drill/extract/tap as she sits but loosen your PS and alternator belts. Lowe's and Ace Hardware has a good bolt selection. They are metric. Use a grade 8 bolt or better. I'll look in the manual and see if I can find the size.

I had a similar issue with a cam gear. The last mechanic didn't tighten that bolt properly. It happens. Oreilly's has a good selection of loaner tools if you need them. So does Advance and AutoZone.

[mitch1204]

   
E7GZ-6A345-A
Bolt - Hex.Head
Use with small shaft Crankshaft-approx. 22mm OD, BEFORE 10/1/90
Fit Note: 1.6L 4 Cyl

F1CZ-6A345-A
Bolt - Hex.Head
Use with large shaft Crankshaft-approx. 27.7mm OD, FROM 10/1/90
Fit Note: 1.6L 4 Cyl

Torque: 109-152 inch lbs.

Try to get one good bolt out for shopping. If not you can Google them part numbers.

Look in our parts forum. There are a couple members parting out their Capris. You might get them to send the bolts and possibly the pulley if the holes are egg shaped.

[SHOwn]

Thanks for the replies Mitch! That info is helpful. Yes the car manufacture date is well past that, (5-91), and I'm thinking it has the long nose crank, but there are doubts since there are conflicting things written about some of this. I have the repair history from previous owners going back a long way, and the water pump & timing belt was put on at 87, 200 which was only 32k ago. However, the WP (or perhaps the lower hose to water pump clamp) leaks a dribble every week for a year and a half now. Maybe because it the temp sensor stopped working two winters ago and I blew a small turbo coolant hose. Nothing got hurt, I was two blocks from my destination and I got it towed home for repairs, but it took me a week in sub-zero temps to realize the sensor caused the hose to burst, so it kept getting a little too warm and overheating a little that week. The next weekend I replaced the sensor and t-stat and all has been good ever since, (except the dribble - a teaspoon a week).

Thanks for the info on tapping the holes. I have a metric tap kit, and have done some repairs previously with it, but I welcome more experienced user input! However, I think I'm going to have to go with bigger bolts if that is possible. I tried putting in another 10 in one of the holes and it is not big enough. I can see the threads if I look at it off-center and they are wallered out some from the way it came apart. I looked at the PDF for the engine section of the repair manual and I'm still not sure what is actually threaded, but I think it is the harmonic balancer.

BTW, I went to remove one of the two remaining bolts and with the slightest of pressure, it snapped off halfway down the bolt shaft. I might need a harmonic balancer if the holes are wallered out too much.

Rock Auto has a DMJ timing belt component set which includes everything - even the water pump and seals for $53. I just have to psyche myself to take this on right now. I'm not the mechanic my dad was, I was a bodyman!

[SHOwn]

Wow, this is a confusing issue! I still have not touched it since breaking bolt #3. I had church and a nice family fall color tour scheduled today, and frankly, those come first. So I haven't done anything yet, but I'm going to go out to the garage and take the belt and pulley off.

After skimming the Miata forum page regarding the issue, I was thinking to not disturb the bolt or gear, but now that I carefully read it, I see he recommends a new bolt after all, so I guess I'll try to get one. I haven't decided if I'll pull the key yet. I am thinking to pull the bolt and if all is well, put it back together, but I haven't examined the pulley threads yet, so I might be pulling a gear from the boneyard. I know where one is, but maybe it is bad too!

I'll keep reporting. Maybe post another pic too.
Ron

[mitch1204]

The gear should be okay. I remember reading a TSB on that center bolt. I'll see if I can't find it. I'm not sure what it said. I do remember they changed the torque. Probably because that small nose issue. Them four bolts don't have much torque. You might get by with loc-tite if the threads aren't chewed up.

[SHOwn]

Really slow progress. Looks to me like this is a long nose crank? I will try to look at it when I get home tonight. If long nosed, the bolt holes should be in a rectangular pattern, if I remember Rocket's info corectly. If is is long, I have to get the main bolt off in order to take the timing belt off, and I'll have to get the stupid ez-out  that I broke in one of the bolt stems out from the back side.

I'm struggling to remove the main crank bolt. My impact just rotates the crankshaft. I tried 5th gear but that did not help. I have the drivers side wheels on the ground and the passengers up right now. I will try lowering the right-rear and putting both fronts on ramps instead of my jack stands. Maybe 5th gear will offer enough resistance then, but I wonder if my clutch might be slipping a tad in this situation. It seems fine on the road, but I never try whole-shots!

[blueamber]

Supposedly the long nose crank can be ID'd by the 8 slot pulley. 

Putting rope through the spark plug hole and jamming the piston always worked for me when removing the crank bolt.

There can be other issues with the long nose crank.  The key and keyway is shared by the timing gear and the pulley assembly.  The short nose crank had the pulleys and crankshaft damper connected to the timing gear.  With all that weight and torque on one small key on a small area of the crank, wallowing occurred at the keyway and key, allowing the timing to change since the gear rotated to a new position.

The long nose crank has a longer keyway and a longer key.  Without the heavy pulley/damper connected to the timing gear, there is really no chance for the timing gear portion of the key/keyway to get damaged.

That being said, I had a 93 na/ long nose, that had a wobbling pulley at the crank.  It turned out that the key under the pulley/damper assembly had snapped in half.  The crankshaft keyway under the pulley was damaged, wallowed out badly.  This allowed the pulley to wobble a bunch, and the damper was toast.  I considered building up the damaged keyway on the crank with some material, install a new key and damper, and go with it.  I wound up junking the car.  170k miles on the car, I had other capris to drive, and couldnt in good consciousness sell an iffy-repaired car to anyone.

Hope you don't see damage to the crank when you get the bolt off...good luck...

[Rocketman]

Didnt have time to read the whole thread - I'll come back and check it later. But i've had this happen a few times to me. B6T's and BP's that produce a lot of power tend to shear these bolts. They're also small, and can be over-tightened and stretched, which can make them snap easy.

The first time I drilled & tapped the holes oversize for 1/4"-20 hardware store bolts.

The second time the sheared bits came off clean.

In the future I plan on drilling out to M8x1.25 and installing studs, which seems better than a bolt for this application.

To remove that big nut, use a ratchet on the crank nose with a piece of pipe. (or a suitable breaker bar) make sure it rests against the chassis. Unplug the ignition coil. Quickly whack the key to engage the starter for a tenth of a second. This will break the main bolt free, but ya gotta be careful

[mitch1204]

Now that you mention that I forgot how I broke my crank bolt loose, lol. I think since I was changing the timing set anyways I put a big wrench on that square spot on the cam and then used a big breaker bar. If you plan on reusing the belt it might stretch it out.

An impact should do wonders.

[SHOwn]

Ok, things are looking up. I went with putting a ramp under the driver's side front wheel, and putting the passenger side front wheel back on and lowered onto another ramp. Then I put it into 5th gear, and cranked on it with my impact. I had to wait for the pressure to peak, and it didn't come off until I popped the Milton fitting and gave it a drop of pneumatic oil, but it did come off.

Better yet, the key, sprocket and crank are all pristine.

I still have one question. Although the Miata short crank webpage says you should replace the crank bolt, is it still possible? I can't find a thing when I Google the part number you provided. Does anyone still stock them?

[SHOwn]

Little more update and another question or two..
Went to the boneyard yesterday and today at lunch and pulled a harmonic balancer/pulley, a/c pulley, the bolt ring, the pulley boss, and the bolts that broke on my car. Joes in Spring Lake has 3 n/a's in mostly intact condition, and another 3 hulks in the corner of the Ford section.

I think I figured out what happened to my car when picking today. The previous mechanic who installed the last owner's timing belt put the bolt ring on the pulley boss first, then the harmonic, then the pulley and finally the bolts. The service manual seems to confuse this by not naming the bolt ring and showing the pretecessor to the pulley boss. The car I stripped at the yard had the bolt ring as the last part on before bolting. This would better clamp the layers of the pulleys together and resist flexing better. Actually, the confusion stems from the design change. The 91 service manual shows the short crank components, while the cars I worked on all have the long nose.

So, another question. Can I re-use the key? It's perfect. I don't know where to get another one new.

[blueamber]

If the key is perfect, I'd re-use it, although keys are a pretty standard hardware item, probably available at a well stocked hardware store... That's great news on the undamaged crank, you should be back on the road in no time...

[SHOwn]

Reuse the main bolt too? Or are new ones actually available?

[azgtx]

This is the time for you to get the upgraded bolt and key. Get it from Mazda for an 88 323 GTX or GT or an early 91 Miata.  When you have it apart  change the front crank seal to stop that oil leak. Might even be the cam seals as well.